Hey everyone, I am getting ready to put in a new clutch.  While I have it out I would like to rebuild my 4 speed.  It kicks out of 3d gear under deceleration, thought this would be my best opportunity.  So any advice?  I am a fair mechanic, but I have never took on a tranny before.  Is there a rebiuld kit available with all new synchro's and stuff?

 

JR

i would certenly first consider the price of a prof rebuild one and the price of a rebuild kit : synchro's,gears, bearings etc.In the first case you have at least the garantee....Keep us posted as if you have a idee in compare the 2 options regarding price ?  

Those prof builders have the experience and know where to have extra attention as for us amateurs it is a big adventure i'm affraid....unless ofcorse you have all the new pieces and a good manual.....

good luck !

 

 

Shark, First off, this may not be the kind of job you would wish to tackle while in the learning phase, especially seeing that 70 m21,s are hard to find if you goof up, the cost of a professional rebuild is not that differant from a do it yourself project especially if you allready have the thing out of the car.Good luck, Rickd

Rebuild kit w/bearings-brass-seals runs around $120-$175, depending on where you shop.
If it's jumping out of gear, it could be that the teeth on the gear itself(synchro mating teeth) are worn, or the synchro coupler("slider")is worn. It can also be caused by worn forks, or excessive end-play in the unit, normaly a result of worn bearings. Or, it can be caused by a shifter not moving far enough to engage the synchro assembly fully. Give up yet?
All internal parts for Muncies(and BW T10) are available new.
There is also a kit available to make the Muncie an overdrive!! Check out this post!
I would suggest checking in your area for prices on rebuild. Labor should be in the neighborhood of $200-$350, if you take the trans in by itself. I have to agree with the others here. Unless you have plenty of spare time to disassemble & re-assemble it several times, I would let an experienced builder do it for you. Adams' Apple38745.9123263889

By all means.  Joel or I would not hesitate, but for a novice it could be very easy to miss something and still have the same problem.  I would recommend pulling it out and go to a pro.  But if you can hook up with someone who has done the job before, you may find it quite an education and a bit of fun to go through it and do the job.  Just have the right help.